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330
NOTES OF A BOTANIST
river. I propose here to treat of the lower part of these two rivers,
and especially of the Chira, in some detail.
The configuration of the coast-region from Cape Blanco to and
beyond the Piura is as follows : On the western margin rise steep
cliffs to a height of from 200 to 300 feet, either directly from the
sea or with an intervening beach uncovered at low-water, and
usually with a low reef of rocks at about half-tide, whereon even
the gentle waves of the Pacific break in a dangerous surf. Having
surmounted the cliff, we are on what is called the tablazo, a
plateau rising very gently to eastward, in some places slightly
undulated, and in others with ridges of considerable height risingout
of it, the whole so bare of vegetation that there are places
where not a single tree, much less an herb, can be distinguished
within the limits of vision. A bold abrupt ridge, called the Silla
de Payta, rises immediately to southward of that town to a height
(according to Captain Kellett) of 1300 feet; but a far more
important range of hills, beginning from near the sea, a little
northward of the mouth of the Chira, runs with a direction
to
of
E.N.E. all the way up between the rivers Chira and Tumbez, till
it mingles with the Andes towards the sources of the latter
river. ... I suppose these hills to rise, even in their western
part (which is all I have seen of them), to from 2000 to 3000
feet; to eastward, as they near the Andes, they must be far
higher. Viewed from the south, they appear entirely
bare of
vegetation, but when they come to be examined their deep
ravines are found to contain a few scattered Cactuses, Algarrobos,
and other trees ; and I am told that on their northern slope there
is considerably more permanent vegetation, much as on the hills
of Chanduy and St. Elena, which, although of far less extent,
have quite the same aspect and structure.
The country to southward of the river Piura is known as the
Despoblado (or Desert) of Sechura : but in reality that term might
be extended to the whole desert region which stretches northward
to the skirts of the forests of the Gulf of Guayaquil, for the narrow
strip of vegetation along the courses of the Chira and Piura are
mere oases in that vast desert.
The deep valley along which the Chira flows to the sea has
plainly been excavated by the action of water, and if any
depression have originally existed on the tablazo along
the same
line it must have been very slight, as there is now no appreciable
sloping towards it. Its sides are steep cliffs, scarcely at all
furrowed transversely on the southern side, but on the northern
side in most places very much broken up into ravines and
alternating peaked ridges, whose origin may be traced to the
effect of the rare but torrential rains descending the rugged slopes